/**
 * JavaScript�ű�ʵ�ֻص�ҳ�涥��ʾ��
 * @param acceleration �ٶ�
 * @param stime ʱ���� (����)
 **/
function gotoTop(acceleration, stime) {
    acceleration = acceleration || 0.1;
    stime = stime || 10;
    var x1 = 0;
    var y1 = 0;
    var x2 = 0;
    var y2 = 0;
    var x3 = 0;
    var y3 = 0;
    if (document.documentElement) {
        x1 = document.documentElement.scrollLeft || 0;
        y1 = document.documentElement.scrollTop || 0;
    }
    if (document.body) {
        x2 = document.body.scrollLeft || 0;
        y2 = document.body.scrollTop || 0;
    }
    var x3 = window.scrollX || 0;
    var y3 = window.scrollY || 0;

    // ��������ҳ�涥����ˮƽ����
    var x = Math.max(x1, Math.max(x2, x3));
    // ��������ҳ�涥���Ĵ�ֱ����
    var y = Math.max(y1, Math.max(y2, y3));

    // �������� = Ŀǰ���� / �ٶ�, ��Ϊ����ԭ��ԽС, �ٶ��Ǵ��� 1 ����, ���Թ��������Խ��ԽС
    var speeding = 1 + acceleration;
    window.scrollTo(Math.floor(x / speeding), Math.floor(y / speeding));

    // ������벻Ϊ��, �������ú���
    if (x > 0 || y > 0) {
        var run = "gotoTop(" + acceleration + ", " + stime + ")";
        window.setTimeout(run, stime);
    }
}